A functional and essential debate

Science does not deal in values and cannot adjudicate on the ethics of abortion. However, abortion is an intervention to halt a biological process; science can describe this process and such understanding is an essential aid to ethical decision-making. I will outline the biological process and also a coherent philosophical position, in my opinion, on abortion. My argument is based on biology and rational analysis. It is motivated by concern for human rights and is not informed by religion.

An individual human life begins at conception when a sperm cell from the father fuses with an egg cell from the mother to form a zygote. This divides into two daughter cells, each daughter divides into two and so the process goes, on and on. After about seven days the developing life implants in the womb where it grows and develops before emerging as a newborn baby. The first three months in the womb is the embryonic stage; after which the developing embryo is a foetus.

Conception is the start of a continuum of an individual human life that ends in death. Under normal circumstances the unfolding along the biological continuum is automatic and self-regulating. Some of the successive stages are zygote, embryo, foetus, baby, child, adult, elderly person. Transitions between these stages are gradual and smooth. This human continuum is fundamentally different from both the preceding sperm and egg cells and the corpse that succeeds it.

The developing entity is unambiguously alive and genetically Homo sapiens from conception and, at every point along the continuum, it has the human properties appropriate to that stage. The full human essence is present everywhere along the continuum. The complete genetic instructions are present in the zygote and guide development along the continuum. I am convinced human life, even at its earliest stages, merits sufficient respect that it not be deliberately killed.

There is (almost) universal agreement that it is morally wrong to deliberately kill a human after birth because you are now dealing with a person. However, many people believe personhood does not exist before a significant stage of foetal development, and consequently hold that killing an embryo or early stage foetus, under circumstances where continuing the pregnancy would cause psychological distress to the mother, is permissible. I believe this argument/position fails under philosophical analysis.

Personhood is typically defined, based on philosophical functionalism, as the capacity to do human things – think, feel, remember, anticipate. The zygote and the early embryo are incapable of these behaviours. Functionalism defines personhood as the ability to do certain things, and the embryo/early foetus is seen as not yet a person. This is often the pro-choice position in the abortion debate. But if the foetus is only a potential person, what is it actually?

Essentialism is an alternative philosophical position that defines a thing according to its essence, not according to its behaviour. In this philosophy, being is actual, functioning is potential. Potential refers to behaviour, not to essence. Thus, personhood, as defined by essentialism, is present all along the human continuum and a zygote or a foetus is a person who is a potential musician, swimmer or singer.

Essentialism harmonises with the smooth biological continuum and with the universal presence of the human essence along the continuum. In my opinion, functionalism confuses being with doing and would, by definition, deny personhood status to a comatose patient, or to a severely intellectually disabled person.

Taking both biology and philosophy into account, I believe the early embryo is a person with potential, not a potential person.

William Reville is an emeritus professor of biochemistry and public awareness of science officer at UCC. understandingscience.ucc.ie